Transmitting and recording method, reproducing method, and reproducing apparatus of information and its recording medium

ABSTRACT

A method of reproducing data from a recording medium, wherein each of the data includes reference time information indicating a reference time and packet information, includes the steps of rearranging the data on a time axis such that a time interval between adjacent data is equal to a difference between respective reference times indicated by the reference time information of the adjacent data, and outputting the rearranged data at an output rate equal to or greater than a data rate of the data. The packet information includes at least video packet information into which a compressed video signal data stream is divided, and audio packet information into which a compressed audio signal data stream is divided.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.10,252,581 filed Sep. 24, 2002, allowed, which is a continuation ofSerial No. 10/051,066 filed Jan. 22, 2002, now U.S. Pat. No. 6,549,579B2, which is a continuation of application Ser. No. 08/463,827 filedJun. 5, 1995, now U.S. Pat. No. 6,438,172 B1, the contents of all ofwhich are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an apparatus for recordingcompressed video and audio signals on a medium such as an optical diskor the like and reproducing such signals from such a medium.

[0003] A compression of video and audio signals has been described indetail in Jun Yonemitsu (editorial supervisor), “MPEG Technique,”pp.19-21, published in Japan by Trikeps on Dec. 21, 1993. An example ofan optical disk has been described in detail in Kenji Hayashi (editorand author), “CD-From Audio to Personal Computer,” pp. 84-89, publishedin Tokyo, Japan, by Corona Publishing Co., Ltd., on Jul. 25, 1990.

[0004] A compression method of the video and audio signals and acorresponding decompression method have been described in the firstreference listed above. A signal recording format of a compact disc (CD)has been described in the second reference listed above. However, amethod of easily realizing a retrieving method when the compressed videoand audio signals are recorded on a medium and are reproduced therefromis not described.

[0005] In the case of reproducing the medium such as a CD or the like onwhich the compressed video and audio signals have been recorded in adata stream format as described in the “MPEG Technique” reference listedabove, a picture or a boundary of a group of pictures can be judged byreproducing the data stream and judging header information of a pack anda packet. In the case of recording a signal on the medium, however, inorder to improve an error resistance, an interleave process and an errorcorrection encoding process which are peculiar to the medium and a frameforming process involving addition of a sync signal and sub informationare ordinarily executed. When the picture or boundary of the picturegroup is judged by reproducing the data stream and judging the headerinformation of the pack and the packet, therefore, a position of apickup or the like which is reproducing data from the medium has alreadybeen deviated. Therefore, in the case of performing a retrieval, anediting operation, and the like on a picture or picture group unitbasis, a complicated control is needed to find a position of the pictureor boundary of the picture group on the medium, so that there is aproblem such that it takes a long time to find the position.

SUMMARY OF THE INVENTION

[0006] It is an object of the invention to provide a transmitting andrecording method, a reproducing method, and a reproducing apparatus ofinformation which are suitable for retrieving and editing on a pictureor picture group unit basis.

[0007] The above object is accomplished by a method whereby, when timesequential data of a pack is divided into a minimum unit of a datastructure which is peculiar to a medium and is transmitted or recordedon the medium, information indicating whether or not a picture or aboundary of a picture group exists in the minimum unit of the datastructure peculiar to the medium is described in a sub informationportion in a frame signal to be transmitted or recorded when a frameforming process that is peculiar to the medium is executed.

[0008] In the case of performing a retrieval, an editing operation, orthe like on a picture or a picture group unit basis, by reading theinformation which was reproduced from the medium and was written in thesub information portion in the frame signal peculiar to the medium andindicates whether or not the picture or the boundary of the picturegroup exists in the minimum unit of the data structure peculiar to themedium and by judging the information, a reproducing position on themedium at which to reproduce the picture or the boundary of the picturegroup can be accurately and easily detected. Thus, a complicated controlto find the position of the picture or the boundary of the picture groupis unnecessary, so that the picture or the boundary of the picture groupcan be retrieved at a high speed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a block diagram showing an embodiment of a transmittingor recording method of information according to the invention;

[0010]FIG. 2 is a block diagram and an explanatory diagram showinganother embodiment of a recording method of information according to theinvention;

[0011]FIG. 3 is an explanatory diagram showing a reproducing method ofinformation according to the invention;

[0012]FIG. 4 is an explanatory diagram showing another embodiment of areproducing method of information according to the invention; and

[0013]FIG. 5 is a block diagram and an explanatory diagram showing anembodiment of a reproducing apparatus of information according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiments of the invention will now be described with referenceto the drawings.

[0015]FIG. 1 shows an embodiment of the invention and shows atransmitting or recording method of information. Reference numeral 1denotes a pack forming process of compression data; 2 a signal processthat is peculiar to a medium; 3 a medium to transmit or recordinformation; 4 compressed video data; 5 compressed audio data; 6independent data such as data or the like which is defined by the user;7, 8, and 9 packet forming processes; 10 a pack forming process; 11 aprocess to divide time sequential data of a pack to a data structurethat is peculiar to the medium; 12 main signal processes such asaddition of an error correction code, interleave, and the like peculiarto the medium; 13 an extracting process of information indicating inwhich component element of a data structure a boundary of a group ofpictures is included when the time sequential data of the pack isdivided to the data structure peculiar to the medium; 14 a frame formingprocess for forming a frame signal peculiar to the medium; 15 a processto add sub information to the frame signal; and 16 a process to add async signal to every frame of the frame signal.

[0016] A method of transmitting information or forming a recordingsignal according to the invention will now be explained herein belowwith reference to FIG. 1.

[0017] In the pack forming process 1 of compression data, a packetheader indicative of a head of the packet is added to each of thecompressed video data, compressed audio data, and independent data,thereby forming packets. Each packet is time divided, one or morepackets are collected, and a pack header indicative of the head of thepack and information indicative of a reference time are further added,thereby constructing a pack. In the signal process 2 peculiar to themedium, the time sequential data of the pack is first divided to thedata structure peculiar to the medium.

[0018] When dividing, an extracting process of information indicating inwhich component element of the data structure the boundary of thepicture group is included is performed. The divided time sequential dataof the pack is subjected to signal processes such as addition of anerror correction code, interleave, and the like in order to enhance anerror resistance in accordance with a signal processing format peculiarto the medium. In order to transmit or record the signal processed data,a frame forming process peculiar to the medium according to a frameformat is performed. In the frame forming process, sub information and async signal indicative of the head of the frame are added to the datawhich was subjected to the signal processes peculiar to the medium,thereby forming a frame signal.

[0019] According to the invention, information indicating in whichcomponent element of the data structure peculiar to the medium theboundary of the picture group is included is inserted in the subinformation of the frame signal at the time of the frame formingprocess. If there is a channel code modulation rule which is suitablefor recording or transmitting data for the frame signal and which hasbeen decided in the medium and which is peculiar to the medium, thechannel code modulation according to the modulation rule is executed forthe data. If there is no channel code modulation rule, data istransmitted or recorded as it is by the medium.

[0020] According to the invention, the information indicating whether ornot the head of data (for example, a group of pictures) of a certainunit of the compressed video data is included in the minimum unit of thedata structure peculiar to the medium can be transmitted or recorded byusing an area to transmit or record the sub information which isdifferent from an area to transmit or record main information in theframe signal peculiar to the medium.

[0021] Another embodiment of the invention will now be described withreference to FIG. 2. The embodiment relates to a case where theinvention is applied to a compact disc (CD), a CD-ROM, or a systemhaving a data structure and a frame format which are equivalent to thoseof the CD-ROM.

[0022] In FIG. 2, reference numeral 20 denotes time sequential data of apack. A boundary between B and C indicates a boundary of a group ofpictures. A head of the C portion denotes a head of data of the picturegroup. Reference numeral 21 denotes a data structure which is peculiarto the medium; A a header section including a sync signal or the like; Band C data to which the time sequential data of the pack is divided andis allocated and which is equivalent to the B and C portions of the timesequential data of the pack; and D other data including a marginsection. Such A, B, C, and D portions indicate minimum units of the datastructure peculiar to the medium and are defined as one block. Accordingto the invention, the number of bytes of one block is set to 2352 bytes.

[0023] Reference numeral 22 denotes a frame signal peculiar to themedium; SY a frame sync signal; SUB a subcode as sub information; and 23a main information portion in the frame signal. In the embodiment, themain information portion 23 has a total of 32 bytes including 24 bytesof data and eight bytes of an error correction code (ECC). It is assumedthat one frame is constructed by such a frame sync signal, subcode assub information, and main information. Reference numeral 24 denotes adata structure of the subcode. The subcode is formed by eight kinds ofcodes such as P, Q, R, S, T, U, V, and W each having a code length of 98bits. Data of eight bits obtained by collecting one bit from each codeis inserted in the SUB portion in the frame signal.

[0024] A recording method of the embodiment will now be explained. Thetime sequential data of the pack is divided every number of bytescorresponding to the number of bytes of the data portion of the block asa minimum unit of the data structure peculiar to the medium, therebyallocating data to the data portion of each block. Upon allocation, itis detected that the boundary between the picture groups B and C existsin the block. A code indicative of the presence of the boundary iswritten, for example, in the Q code in the subcode. At the same time,the block formed data is subjected to the signal processes such asaddition of an error correction code, interleave, and the like peculiarto the medium. When the signal processed data is frame formed, such datais allocated to the main information portion of the frame signal.

[0025] At the same time, the subcode is allocated to the SUB portion bythe foregoing method. As mentioned above, the information indicative ofthe boundary of the picture group can be written in the subcode portionof the frame signal. The frame signal constructed as mentioned above issubjected to, for example, an 8-14 modulation (EFM) such that eight bitsare allocated to 14 bits and, after that, the signal is recorded on amedium such as a CD or the like. According to the invention, informationindicating whether or not the head of the picture group of thecompressed video data is included in the block as a minimum unit of thedata structure peculiar to the medium can be recorded on a CD, a CD-ROM,or a system having a data structure and a frame format which are similarto those of the CD-ROM by using an area to record the sub information inthe frame signal peculiar to the medium.

[0026] The embodiment has been explained with respect to the case wherethe information indicative of the presence of the boundary is describedin the subcode Q. However, even if such information is described in anyone of the codes P, Q, R, S, T, U, V, and W without limiting it to the Qcode, a similar effect is obtained. For example, a data start flag isdescribed in the P code in the present CD. Information indicative of thepresence of the boundary can be described in place of such a flag or ina portion of such a flag. By describing the serial number or an addressof the head of the picture group of the compressed video data instead ofthe information indicative of the boundary, an even more accurateretrieval can be performed upon reproduction.

[0027] By not only describing the information indicative of the boundaryand the serial number or address of the head of the picture group of thecompressed video data but also simultaneously adding and describing aCRC code to detect reproduction errors of those data, a degree ofaccuracy of those data which are reproduced at the time of the retrievalcan be improved. In the case where the information indicative of theboundary or the serial number or address of the head of the picturegroup of the compressed video data is recorded in the Q code, bydescribing them in place of the portion in which PMIN, PSEC, and PFRAMEindicative of the minute, second, and frame of the reproducing time havebeen written in the present CD, the reproduction errors can be detectedby the CRC code of the Q code in this state. Although graphicinformation has been described in the codes R, S, T, U, V, and W in thepresent CD, the information can be also described in such portions by amethod similar to that of the P code described above.

[0028] Another embodiment of the invention will now be described withreference to FIG. 3. FIG. 3 shows a reproducing method according to theinvention. Data reading intervals shown by 31 and 33 are intervalsduring which a reproducing apparatus reproduces data on a medium. Aportion indicative of a high speed movement of a data reading position32 is an interval during which the reproducing apparatus moves thereproducing position of data on the medium for a high speed retrieval.After the data reading position has been moved at a high speed upon highspeed retrieval, the reproducing apparatus retrieves a target positionon the medium while repeating the operation to read data.

[0029] According to the invention, in such a data reading interval,information which has been written in the sub information in the framesignal peculiar to the medium and which indicates whether or not thehead of the data (for example, a picture group) of a certain unit of thecompressed video data is included in the minimum unit of the datastructure peculiar to the medium is judged and, on the basis of suchinformation, the boundary of data of a certain unit of the compressedvideo data can be retrieved from the medium at a high speed. Accordingto the embodiment, there is an effect such that the boundary of the dataof the certain unit of the compression video data can be retrieved fromthe medium at a high speed.

[0030] Another embodiment of the invention will now be described withreference to FIG. 4. FIG. 4 shows a reproducing method according to theinvention. The embodiment relates to a case where the reproducing methodof the invention is applied to a CD, a CD-ROM, or a system having a datastructure and a frame format which are similar to those of the CD-ROM.In FIG. 4, the same component elements as those in FIGS. 2 and 3 aredesignated by the same reference numerals.

[0031] In a manner similar to the embodiment shown in FIG. 3, thereproducing apparatus retrieves a target position on the medium whilerepeating the operation to read data after the data reading position hasbeen moved by moving a pickup at a high speed upon high speed retrieval.A frame signal which is reproduced from the disk for the data readinginterval is the same signal as the frame signal shown in FIGS. 2 and 4.

[0032] As for the subcode, the subcodes each comprising eight bitswritten in each frame for 98 frames are collected, thereby reproducingeight subcodes of P, Q, R, S, T, U, V, and W in which one code consistsof 98 bits. Information which has been described in any one of thosesubcodes and indicates whether or not the head of the picture group ofthe compressed video data is included in the block as a minimum unit ofthe data structure peculiar to the medium is reproduced and a boundaryof the picture group is judged, so that the boundary of the picturegroup can be retrieved at a high speed. According to the embodiment,there is an effect such that the boundary of data of a certain unit ofthe compressed video data can be retrieved from the medium at a highspeed.

[0033] Another embodiment of the invention will now be described withreference to FIG. 5. FIG. 5 shows a reproducing apparatus according tothe invention. This embodiment relates to a case where the reproducingapparatus of the invention is applied to a CD, a CD-ROM, or a systemhaving a data structure and a frame format which are similar to those ofthe CD-ROM. In FIG. 5, reference numeral 51 denotes an optical disk; 52a signal processing section peculiar to the medium; 53 a subcode judgingsection; 54 a pickup control section; 55 a pickup; 56 a memory; 57 awrite address generating section; 58 a read address generating section;59 an address comparator; 60 an output time adjusting section of timesequential data of a pack; 61 a reference clock; and 62 a clock peculiarto the medium.

[0034] The operation at the time of a high speed retrieval will be firstdescribed. Upon high speed retrieval, a frame signal reproduced from theoptical disk 51 in the data reading interval is inputted to the signalprocessing section 52 peculiar to the medium, thereby separating asubcode and main information on the basis of a sync signal in the framesignal. The subcode is inputted to the subcode judging section 53,thereby judging whether or not the subcode indicates a boundary of apicture group. When the subcode does not indicate the boundary of thepicture group, the pickup 55 is moved at a high speed by the pickupcontrol section 54 and the judgment of the subcode is repeated. In thecase where the subcode does indicate the boundary of the picture group,reproduction is performed. As mentioned above, the retrieval can beperformed on a picture group unit basis.

[0035] The operation upon reproduction after completion of the retrievalwill now be described. The reproduced frame signal is inputted to thesignal processing section 52 peculiar to the medium and the subcode andthe main information are separated on the basis of the sync signal inthe frame signal. After that, the main information is subjected toprocesses such as error correction, deinterleave, and the like, therebyreproducing data of a block structure as a data structure peculiar tothe medium. The data of the block structure is stored into the memory 56in accordance with a write address which is generated by the writeaddress generating section 57 on the basis of the clock 62 peculiar tothe medium and the reference clock 61. The data stored in the memory 56is read out in accordance with a read address which is generated by theread address generating section 58 on the basis of the reference clock61 and is inputted to the output time adjusting section 60 of the timesequential data of the pack.

[0036] The write address and read address of the memory are alwayscompared by the address comparator 59. When the write address differsfrom the read address by a predetermined amount or more, the pickup 55is controlled by the pickup control section 54 to temporarily stop thereproduction. A speed to read the data from the optical disk 51 isalways set to be equal to or larger than the maximum data transfer rateof the time sequential data of the pack and the reproduction controldescribed above is executed, so that an excessive data or a lack of databetween the reproducing apparatus and a decoding apparatus of the timesequential data of the pack to which an output of the reproducingapparatus is connected can be absorbed.

[0037] The data read out from the memory 56 is subjected to time basecorrection by the output time adjusting section 60 of the timesequential data of the pack. Reference numeral 63 shows a time basecorrection of the time sequential data of the pack. In the output timeadjusting section 60 of the time sequential data of the pack, a timeinterval between the heads of adjacent packs is corrected with respectto the time base so as to be almost equal to a difference between thereference times in accordance with the reference time described in everypack of the data read out from the memory 56. Since an amount of data ofone pack may be different for every pack, the data is outputted at themaximum data transfer rate in the time sequential data of the pack. Inthe case of a pack having a small amount of data, invalid data isoutputted in the portion between the end of the pack to the head of thenext pack or the data is outputted so as to indicate that such a portioncontains invalid data. For instance, such a process can be realized by amethod such that a signal indicative of valid or invalid data andsynchronized with the data is generated together with the data, anidentification signal is added to the invalid data portion, or the like.According to the embodiment as mentioned above, the reproducingapparatus which can retrieve the boundary of the picture group at a highspeed and can perform a normal reproduction can be constructed.

[0038] Explanations will now be made with reference to FIG. 5 withrespect to a case where when a video signal is compressed, for example,encoded data is recorded on an optical disk while changing a datacompression ratio for every picture group and is reproduced by thepresent method.

[0039] A Group of Pictures (GOP) is constructed as a picture group byusing several video frames as a unit. A compression ratio is changed ona GOP unit basis, thereby compressing the video signal. The compressedvideo signal is subsequently divided into several packs. A referencetime signal is added to the head of the pack and the pack is recorded.On the optical disk 51, the recording is executed at a constantrecording density irrespective of the packs of the GOP of differentcompression ratios.

[0040] Upon reproduction, an output time of the time sequential data ofthe pack is adjusted so that a time interval between the heads of thepacks is equal to a time difference between the reference time signalsadded to the heads of the packs.

[0041] By executing the reproduction as mentioned above, the dataencoded so that the compression ratio of the data is changed on a GOPunit basis can be also accurately reproduced.

[0042] Although the embodiment relates to an example of the case whereone GOP is set to one pack, in the case of recording data of one GOP bydividing it to several packs, the data can be also reproduced in asimilar manner.

[0043] According to the invention, the information indicating whether ornot the head of data (for example, the picture group) of a certain unitof the compressed video data is included in a minimum unit of the datastructure peculiar to the medium can be transmitted or recorded by usingan area to transmit or record the sub information which is differentfrom an area to transmit or record the main information in the framesignal peculiar to the medium. According to the invention, the boundaryof the data of a certain unit of the compressed video data can beretrieved at a high speed from the medium. Further, the reproducingapparatus which can retrieve the boundary of the picture group at a highspeed and perform a normal reproduction can be constructed.

[0044] While example embodiments may be described herein, it isunderstood that such is presented by way of illustration only, and arenot to be taken as limiting or exhaustive in any way. Manymodifications, adaptations, variations and equivalents are apparent asbeing well within the scope of the appended claims.

What is claimed is:
 1. A method of reproducing data from a recordingmedium, each of the data including reference time information indicatinga reference time and including packet data, the method comprising:reproducing the data from the recording medium; obtaining a differencebetween respective reference times indicated by the reference timeinformation of the reproduced adjacent data; rearranging the data on atime axis such that a time interval between adjacent data is equal tothe obtained reference time difference; and outputting the rearrangeddata.
 2. A method according to claim 1, wherein the packet data includesat least video packet data into which a compressed video signal datastream is divided, and audio packet data into which a compressed audiosignal data stream is divided.
 3. An apparatus for reproducing data froma recording medium, the data including reference time informationindicating a reference time and including packet data, the apparatuscomprising: a reproducing circuit which reproduces the data from therecording medium; a memory which stores the data reproduced by thereproducing circuit; and an outputting circuit which reads the data fromthe memory, obtains a difference between respective reference timesindicated by the reference time information of the read adjacent data,rearranges the data on a time axis such that a time interval betweenadjacent data is equal to the obtained reference time difference, andoutputs the rearranged data.
 4. An apparatus according to claim 3,wherein the packet data includes at least video packet data into which acompressed video signal data stream is divided, and audio packet datainto which a compressed audio signal data stream is divided.
 5. A methodof outputting received data including reference time informationindicating a reference time and including packet data, the methodcomprising: obtaining a difference between respective reference timesindicated by the reference time information of the received adjacentdata; rearranging the data on a time axis such that a time intervalbetween adjacent data is equal to the obtained reference timedifference; and outputting the rearranged data.
 6. A method according toclaim 5, wherein the packet data includes at least video packet datainto which a compressed video signal data stream is divided, and audiopacket data into which a compressed audio signal data stream is divided.7. An apparatus for outputting received data including reference timeinformation indicating a reference time and including packet data,wherein the outputting apparatus obtains a difference between respectivereference times indicated by the reference time information of thereceived adjacent data, rearranges the data on a time axis such that atime interval between adjacent data is equal to the obtained referencetime difference and outputs the rearranged data.
 8. An apparatusaccording to claim 7, wherein the packet data includes at least videopacket data into which a compressed video signal data stream is divided,and audio packet data into which a compressed audio signal data streamis divided.
 9. A method of reproducing data from a recording medium, thedata including reference time information indicating a reference timeand including packet data, comprising: reproducing the data from therecording medium; when a difference between respective reference timesindicated by the reference time information of the reproduced adjacentdata is T1, rearranging the data on a time axis such that a timeinterval between adjacent data is equal to T1 and outputting therearranged data; and when a difference between respective referencetimes indicated by the reference time information of the reproducedadjacent data is T2 (not equal to T1), rearranging the data on a timeaxis such that a time interval between adjacent data is equal to T2 andoutputting the rearranged data.
 10. An apparatus for reproducing datafrom a recording medium, the data including reference time informationindicating a reference time and including packet data, comprising: areproducing circuit which reproduces the data from the recording medium;a memory which stores the data reproduced by the reproducing circuit;and an outputting circuit which reads the data from the memory, when adifference between respective reference times indicated by the referencetime information of the read adjacent data is T1, rearranges the data ona time axis such that a time interval between adjacent data is equal toT1, and when a difference between respective reference times indicatedby the reference time information of the read adjacent data is T2 (notequal to T1), rearranges the data on a time axis such that a timeinterval between adjacent data is equal to T2 and outputs the rearrangeddata.
 11. A method of outputting received data including reference timeinformation indicating a reference time and including packet data, themethod comprising: when a difference between respective reference timesindicated by the reference time information of the received adjacentdata is T1, rearranging the data on a time axis such that a timeinterval between adjacent data is equal to T1 and outputting therearranged data; and when a difference between respective referencetimes indicated by the reference time information of the receivedadjacent data is T2 (not equal to T1), rearranging the data on a timeaxis such that a time interval between adjacent data is equal to T2 andoutputting the rearranged data.
 12. An apparatus for outputting receiveddata including reference time information indicating a reference timeand including packet data, wherein: when a difference between respectivereference times indicated by the reference time information of thereceived adjacent data is T1, the outputting apparatus rearranges thedata on a time axis such that a time interval between adjacent data isequal to T1 and outputs the rearranged data; and when a differencebetween respective reference times indicated by the reference timeinformation of the received adjacent data is T2 (not equal to T1), theoutputting apparatus rearranges the data on a time axis such that a timeinterval between adjacent data is equal to T2 and outputs the rearrangeddata.